Instead, the character of a flow should typically be determined by a single Reynolds number, Re = U L/ ν , where U is the characteristic speed of the flow (measured say in cm/sec ), L is a characteristic size (measured say in cm ), and ν is the kinematic viscosity of the fluid. For water, ν = 0.01 , for air ν = 0.15 , and for glycerine ν = 10000 , all in units of cm 2 /sec .